Apparatus for enlarging well bores



y 1956 A. w. KAMMERER, JR 235% APPARATUS FOR ENLARGING WELL BORES Filed Aug. 25, 1954 2 Sheets-Sheet l 6 70 ENTOR.

,5 ARCHER W mad/145252, rz,

6' li //I July 17, 1956, A. w. KAMMERER, JR 2,755,071

APPARATUS FOR ENLARGING WELL BORES Filed Aug. 25, 1954 2 Sheets-Sheet 2 IN V EN TOR.

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17a BY 6 T g w United States Patent APPARATUS FOR ENLARGING WELL BORES Archer W. Kammerer, Jr., Fullerton, Califi, assiguor, by

direct and mesne assignments, to Rotary Oil Tool Company, Huntington Park, Califi, a corporation of Caliornia Application August 25, 1954, Serial No. 452,182

15 Claims. (Cl. 255-76) The present invention relates to rotary drill bits, and more particularly to bits having outwardly expansible cutters capable of drilling holes below a string of well casing to a greater diameter than the inside diameter of the well casing.

Rotary expansible drill bits are known having cutters occupying a retracted position during movement of the bit through a string of well casing disposed in a bore hole, the cutters being expanded outwardly (after having been disposed below the lower end of the casing string) to drill or enlarge the hole to a greater diameter than the inside diameter of the casing. Particularly with bits embodying cutters of the roller type, the size of the roller cutters has heretofore been limited because of the necessity for confining them in retracted position within the confines of the body during movement of the bit through the well casing. Specifically, space limitations within the body have heretofore dictated the maximum diameter and length of a cutter that could be assembled in the bit. A relatively short length of cutter requires that it be expanded outwardly to a relatively short distance since it is capable of increasing the hole diameter by only a relatively small amount. A comparatively small diameter cutter possesses less strength and cutting teeth, which imparts a relatively short life to the cutter, imposing serious limitations on the length of the. hole that can be enlarged with it before replacement becomes necessary.

Accordingly, it is an object of the present invention to provide a rotary expansible drill bit embodying roller cutters capable of being substantially fully retracted within the bit body, and which have a greater length, to en- 'able them to be expanded outwardly to a greater extent and be capable of greatly enlarging the hole diameter, the bit being capable of directing circulating fluid to its lower portion below the cutters.

Another object of the invention is 'to provide a rotary expansible drill bit capable of discharging fluid from the lower end and embodying roller cutters of greater length, or greater diameter, or both greater length and greater diameter than cutters heretofore used, the cutters being substantially fully retractable within the confines of the 'bit body.

A further object of the invention is to provide an improved rotary expansible drill bit, in which circulating 'fluid can be directed through the lower end of the bit to insure proper flushing of the cuttings to the top of the well bore.

Another object of the invention is to provide an improved combination bit to drill the central orpilot portion of the hole and .to enlarge such pilot portion to a diameter greater than the inside diameter of the well casing through which the bit is moved to a point therebelow, where the drilling operation is to be performed.

Still a further object of the invention is to provide an improved combination bit of the type just indicated, in which circulating fluid can be directed to the cutters of the lower portion of the bit :or on the hole bottom, and

2,755,071 Patented July 17, 1956 also directly against the cutters that are enlarging the pilot or central portion of the hole.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a longitudinal section through an embodiment of the invention disposed in a well bore, with the cutters and other parts in their initial retracted positions;

Fig. 2 is a longitudinal section similar to Fig. 1, disclosing the cutters expanded and locked outwardly in such fully expanded position;

Fig. 3 is an enlarged longitudinal section through the lower portion of the drill bit, with the cutters in expanded position;

Fig. 4 is a longitudinal sectiontaken along the line 44 on Fig. 3;

Fig. 5 is a cross-section, on an enlarged scale, taken along the line 5-5 on Fig. 1;

Fig. 6 is a cross-section, on an-enlarged scale, taken along the line 66 on Fig. 1-.

A rotary drill bit A is attachable to the lower end of a string of drill pipe B, by means of which it is lowered through a well casing C in a well bore D to a point below the casing shoe E at which the drilling operation is to be performed. The drill bit apparatus includes a lower pilot bit portion 10- for centering the tool in a hole ,that may have already been drilled, or for drilling the central portion of a new hole, in the absence of a preexisting hole. It also includes an expansible drill bit portion .11 that is to enlarge the bore hole by producing a formation shoulder F therein and then operating upon the formation shoulder thus produced, in the manner described hereinafter.

The upper end of the drill bit apparatus includes a driving mandrel 12 having an upper pin 13 threadedly connected to the lower end of the drill pipe string B. This mandrel includes an upper kelly or drill stern member 14 slidably splined to the elongated main body 15 of the bit. The lower portion 16 of theexterior of the kelly is hexagonally shaped, being telescopically received in a companion hexagonal socket 17 formed in the body .of the tool. The mandrel 12 has a limited range of longitudinal movement within the body 15, the extent of its upward movement being determined by engagement of an external shoulder 18 on the kelly portion 14 with a retainer ring 19 secured to the upper end of the body, as by the use of welding material 20.

The body 15 has a plurality of expansible parts mounted on it comprising cutter supporting members 21 pivotally mounted in body slots 22 on hinge pins 23 secured to the body. Each hinge pin 23 extends trans versely across a body slot 22, being inserted through a transverse bore 24, with one end engaging a body shoulder 25, the other end being engaged by a split snap retainer ring 26 inserted in a groove 27 surrounding the bore. By contracting the snap retainer ring 26, it may be removed from the groove 27, allowing the pin 23 to be removed from the bore 24 when the cutter supporting members 21 are to be dismantled from the body 15.

Each cutter supporting member 21 depends from its hinge pin 23 and has a bearing supporting pin 28 at its lower end inclined inwardly and downwardly, and on which the side roller cutter 29 is rotatably mounted.

Anti-friction roller and ball bearing elements 30, 31 are disposed between each cutter 29 and bearing pin 28, the roller bearing elements 30 transmitting radical thrusts and the ball bearing elements 31 both radial and axial thrusts. The manner of inserting and retaining the roller and ball bearing elements 30, 31 in place forms no part of the present invention and need not be described in detail. One manner of assembling and holding the cutters 29 on the bearing supporting pins 28 can be found in Patent No. 2,545,036, to which attention is invited.

Normally, the cutter supporting members 21 and their cutters 29 tend to remain in a retracted position substantially entirely within the confines of the body 15 under the influence of gravity. However, the cutter supporting members and cutters are expandible outwardly upon downward and relative movement occurring between the driving mandrel 12 with respect to the body 15 and the cutter supporting members 21 themselves. The cutter supporting members 21 have inner expander surfaces 32 inclined downwardly and inwardly, and which are engageable by an expander and lock member 33 provided on a tubular member 34 of the mandrel 12, the upper portion 35 of which is piloted in the kelly 14. As the lock portion 33 of the tubular member 34 moves relatively downward of the cutter supporting members 21, it will engage the inclined expander surfaces 32 and shift the cutter supporting members 21 and cutters 29 outwardly to their maximum extent, at which time the expander and lock member 33 will be disposed behind locking portions 36 on the cutter supporting members immediately below their expander portions 32, in order to hold the cutter supporting members 21 and cutters 29 in their outwardly expanded positions.

The lower portion 37 of the tubular member 34 is slidable within a body support 38 extending transversely across the slotted region of the body. This support 38 may have a guiding liner or bushing 39 therein, the upper end of which engages a shoulder 40 in the support, and the lower end of which is engaged by a split retainer ring 41 disposed within a groove 42 in the support 38. The lower portion 37 of the tubular member makes a sliding fit in the liner or bushing 39.

The upper end 35 of the tubular member 34 is connected in swivel fashion to the kelly 14, to permit slight relative arcuate or rotary movement therebetween. However, the kelly 14 and tubular member 34 are coupled together for longitudinal movement in both directions. This is accomplished by providing an anti-friction thrust bearing between the upper end or boss 35 of the tubular member and the kelly. The boss is received within a lower socket 43 in the kelly and has a toroidal raceway 44 on its exterioraround which a plurality of bearing balls 45 can ride. These balls are also received in an opposed toroidal raceway 46 in the kelly. The balls 45 are insertible into the raceways through a kelly passage 47 extending through the external shoulder 18 on the kelly and communicating with the internal race 46. After the balls have thus been disposed in position, the hole 47 is closed by a suitable plug 48, which is prevented from moving outwardly of the kelly by the inner wall 150 of the surrounding body 15.

The arrangement between the tubular member 34 and kelly 14 is such that bodily downward and upward movement is transmitted between the kelly and tubular member from one raceway 44 or 46, through the ball bearing elements 45, to the other raceway 46 or 44. In this manner, the kelly 14 and the tubular member 34 are caused to move jointly in both longitudinal directions, but they are free to partake of relative movement therebetween to allow the proper alignment and engagement between the faces 330 on the expander and lock member 33 and the companion inclined expander surfaces 32 and lock surfaces 36a on the cutter supporting members 21.

Relative downward movement of the mandrel 12 and its expander and lock member 33 with respect to the body 14 and the cutter supporting members 21 is accomplished, in the form of invention specifically disclosed in the drawings, by means of a tension spring 50 encompassing the tubular member 34 and secured to the lower portion of the boss 35 of the latter and also to the body 15 of the tool. Thus, the upper portion 51 of the helical tension spring extends upwardly within the kelly socket 43 formed within the lower skirt portion 52 of the latter, which depends below the tubular member boss 35 to a substantial extent. The lower portion 53 of the boss 35 is reduced in external diameter and is provided with an external groove 54 formed as a thread corresponding in pitch to the pitch of the upper spring turns 51 when the latter are collapsed against one another. The upper turns of the tension spring are threaded onto the external thread 54 of the boss, such turns of the spring being incapable of being removed from the boss 35 since their outer surfaces are closely adjacent the inner wall of the socket 43, which prevents the turns 54 from moving laterally outward to the extent whereby they can become disengaged from the boss thread groove 54.

The lower end 55 of the spring is anchored to the body through the agency of an intervening retainer device, in the form of a sleeve 56 resting upon a lower body shoulder 57 and secured to the body by means of a transverse pin 58 that is disposed partially within an external groove 59 in the retainer device and partially within an internal groove 60 in the body. This retainer device 56 has a lower inwardly directed flange portion 61 provided with an internal groove 62 formed as a thread corresponding to the pitch of the lower spring turns 55 when the latter are collapsed against one another. These lower turns 55 are threaded into the internal thread 62, their inner surfaces being disposed closely adjacent the periphery of the tubular member 34. The clearance between the inner surfaces 55 of the lower turns and the tubular member 34 is relatively small, so that the spring turns 55 will engage the tubular member before they can shift laterally inward out of the internal thread 62.

In view of the structure just described, the upper end of the spring 50 is secured to the boss portion 35 of the tubular member 34, and its lower end is secured to the body 15.

When the mandrel 12 is in its uppermost position with respect to the body 15, as determined by engagement of the shoulder 18 with the retainer ring 19, the tension spring 50 is capable of exerting a substantially large tensile force tending to shift the mandrel 12 downwardly of the body 15 and the cutter supporting members 21. When the mandrel 12 is in its uppermost position within the body, the expander and lock portion 33 of the tubular member is disposed at the upper end of the inclined expander surfaces 32 on the cutter supporting members. During lowering of the apparatus through the well casing C, the tension spring 50 is urging the expander member 33 against the upper regions of the inclined expander surfaces 32, but the cutters 29 cannot expand outwardly at this time because the outer surfaces of the cutter supporing members 21 will merely ride along the wall of the well casing. However, when the apparatus has been lowered below the casing shoe E, its further descent is stopped and the drill pipe B rotated, to rotate the apparatus A. The spring 50 is urging the expander member 33 longitudinally along the inclined expander surfaces 32, urging the supporting members 21 laterally outward to cause the cutters 29 on their lower ends to engage the wall of the well bore D. As rotation of the drill pipe B and the apparatus A continues, the cutters will remove the formation material and enlarge the wall of the well bore to the maximum extent determined by engagement of stop shoulders 65 on the cutter supporting members 21 with companion shoulders 66 formed on the body 15 on opposite sides of the body slots 22.

As the cutters 29 moved outwardly, the expander member 33 moves longitudinally downwardly along the body 15 and the cutter supporting member expander surfaces 32. When the cutters and supporting members have been expanded outwardly to their maximum extent, the expander member is disposed behind the inner locking surfaces 36a adjacent the lower end of the expander surfaces 32. These surfaces 36a are substantially parallel to the axis of the drill bit when the cutter supporting members 21 have been expanded outwardly to their maximum extent, so that there is substantially no reactive force of the formation on the cutters 29 that can shift the cutters inwardly from their maximum retracted position, so long as the expander member 33 remains behind the lock portions 36 of the cutter supporting members.

At the time that the cutter supporting members 21 have been expanded outwardly to their maximum extent, the lower end 67a of the kelly 14 will engage the upper end of the retainer device 56, which allows the drilling weight, which can now be imposed on the drill bit, to be transmitted directly through the body 15 and through the stop shoulders 66, 65 to the cutter supporting members 21 and cutters 29. The drill pipe B is then rotated, to rotate the mandrel 12, the body 15 of the tool, the cutter supporting members 21 and the cutters 29, the cutters rolling around the annular shoulder F formed in the bore hole D to drill away the formation material and enlarge the well bore along the desired length.

The width of the annular shoulder F on which the cutters 29 can operate effectively depends upon the length of the cutters. Heretofore, there have been limitations on the length of the cutters, inasmuch as they must be substantially fully retracted within the confines of the body 15 of the tool. In view of the desirability of pumping drilling mud, or other circulating fluid, to the bottom of the apparatus A, a restriction has been imposed within the body 15 of the tool that precluded the inward extension of the cutters 29 to their maximum extent, and thereby resulted in the use of comparatively short cutters. Such restriction Within the body of the tool also placed a limitation on the diameter of the cutters 29 that could be used, as well as the corresponding tooth surfaces for operation upon the formation shoulder.

The foregoing difiiculties are overcome in the present instance. The drilling fluid pumped down the drill pipe B can pass through the kelly passage 67 and the central passage 68 through the tubular member 34 of the tool, and will be discharged from the lower end of the latter into the well bore, for the purpose of carrying the cuttings upwardly around the tool A and the drill pipe B to the top of the hole. In the present case, the lower end 69 of the tubular mandrel 34 is disposed above the cutters 29 when the latterare in their retracted positions. Accordingly, the cutters can be made of a greater length than heretofore, since their inner portions can be disposed closely adjacent one another and the axis of the body when the cutter supporting members 21 and the cutters 29 are in their fully retracted positions within the confines of the bit body. As the cutters 29 are expanded out- Wardly, they separate from one another, leaving a gap that allows the tubular member 54 of the mandrel 12 to move downwardly and to be piloted within the lower portion of the apparatus, for the purpose of directing the fluid in a most effective manner into the well bore and onto the cutters 29. Specifically, the lower end 69 of the tubular member 34 becomes piloted within a lower bit structure secured to the body, following the outward expansion of the supporting members 21 and cutters 29 to their maximum extent.

The lower portion of the body 15 below the slots may be formed as an annular member 70 having a central bore 71 therein and also a depending reduced diameter portion 72 to form a downwardly directed shoulder 73.

The pilot bit 10 is secured to the lower portion 70 of the upper body by forming the upper portion 74 of the pilot bit body 75 as an annular member that may have substantially the same external diameter as the lower portion 76) of the body 15, and which has a counterbore 76 therein adapted to receive the reduced diameter portion 72 of the body 15, the upper end of the pilot bit body engaging the upper body shoulder 73. The two bodies 1.5, 75 can be secured together, as by running a welding bead 77 completely around the region where the two bodies abut.

The pilot bit 10 has a plurality of roller tooth cutters 78 rotatably mounted on the body in any suitablemanner, these cutters being adapted to engage the bottom G of the well bore D to drill the pilot or central portion of the well bore, or, if there is a preexisting well bore, to assist in centering the drill bit A within the latter, to assure the smooth operation of the upper cutters 29 in enlarging the well bore concentrically with the axis of the preexisting hole. Thus, the pilot bit 10 will produce the lower central portion of the well bore, which will then be enlarged by the upper cutters 29 when they are expanded outwardly to their maximum extent.

Circulating fluid is directed from the passage 68 in the tubular member onto the bottom G of the well bore. It is also preferred to direct such circulating fluid directly onto the expanded cutters 29. Thus, a nozzle or fluid distribution assembly 78 is mounted within the bore 71 of the lower portion 70 of the upper body 15. This nozzle assembly includes a main supporting member 79 adapted to slidably fit within the central bore 71 of the lower portion of the body. The supporting member 79 has a downwardly facing shoulder 80 engaging the upper end of the annular body portion 70, the supporting member carrying an expansible retainer ring 81 in a peripheral groove 82 which is engageable with a downwardly facing shoulder 83 formed in'the body. By virtue of this construction, the upper supporting member shoulder 80 prevents the nozzle assembly 78 from moving downwardly of the body 15, whereas the retainer ring 81 engages the shoulder 83 to prevent upward movement of the assembly.

The assembly 78 extends upwardly from the lower portion of the body and has an enlarged central passage or chamber 84 therein adapted to slidably receive the lower end 69 of the tubular member 34 when the mandrel 12 has been shifted downwardly to its fullest extent within the body 15 of the tool, as a result of outward expansion of the cutter supporting members 21 and cutters 29 to their maximum extent. Leakage between the lower end 69 of the tubular member and the nozzle supporting member 79 may be prevented by a sealing member 85, in the form of a rubber 0 ring, disposed within a groove 36 in the supporting member and engaging the periphery of the tubular member 34.

Fluid from the tubular member 34 will discharge into thecentral passage 84 of the nozzle supporting member 79, this passage communicating with a plurality of nozzles 87 opening out through the lower end of the supporting member, to direct fluid between the lower cutters 78 onto the bottom G of the well bore D, flushing cuttings from the bottom area and maintaining it in a comparatively cutting-free condition, to allow maximum penetration of the lower cutters 78 into the bottom of the well bore. The circulating fluid then passes upwardly around the apparatus A to carry the cuttings from the expansible cutters 29 upwardly to the top of the well bore.

Fluid may also be caused to impinge directly upon the cutter teeth of the expansible cutters 28, when they have been expanded outwardly to their maximum extent. Thus, the supporting member 79 of the nozzle assembly has a plurality of nozzles 88, each of which is inserted through a lateral bore 89 opening into the central passage 84 in the supporting member, and being welded or otherwise secured to the supporting member. Each nozzle 88 is aimed at the teeth of a cutter 29 substantially where they engage the formation shoulder F, to remove the cuttings from the teeth and the shoulder F and flush them to the top of the well bore. As disclosed, the nozzles 88 are inclined in an outward direction slightly upwardly, to remove the cuttings more eflectively from the region of the formation shoulder. D

In the operation of the apparatus, it is lowered in the well casing C with the mandrel 12 occupying its uppermost position within the body 15, and with the tens on spring 50 exerting relatively great tensile force, tendlng to shift the mandrel 12 in a relative downward direction within the body 15. Actually, of course, the tens on spring 50 is tending to shift the body 15 and supporting members 21 in an upward direction relative to the mandrel 12. However, as explained above, the outer surfaces of the cutter supporting members 21 engage the wall of the well casing C, which prevents any substantial relative downward movement of the mandrel with respect to the body and the cutter supporting members. During the descent of the apparatus in the well casing, the lower end 69 of the tubular mandrel 12 is disposed above the cutters 29, which, as explained above, allows cutters of greater length and diameter to be used, and also allows the expander surfaces 32 to be sloped to such an extent as to shift the cutter supporting members 21 and cutters 29 outwardly to a greater extent than heretofore.

When the cutter supporting members 21 have been disposed below the casing shoe E, the tension spring 50 tends to elevate the body 15, cutter supporting member 21 and cutters 29 with respect to the mandrel 12, causing the expander member 33 to engage the inclined expander surfaces 32 and expand the cutter supporting members 21 and the cutters out against the wall of the well bore D. The drill pipe B and apparatus A then are rotated, the cutters 29 commencing to enlarge the well bore by producing the formation shoulder F therein. As the cutters move further outwardly, the spring 50 pulls the body 15, cutter supporting members 21 and cutters 29 further upward relative to the mandrel 12, causing the lock and expander member 33 on the latter to shift the cutter supporting members and cutters further outwardly until they have been expanded to their fullest extent, as determined by engagement of the stop members 65 on the cutter supporting members with the companion stop portions 66 on the body of the tool, and engagement of the lower end 67a of the kelly with the upper end of the retainer device 56 secured to the body. At this time, the lower portion 69 of the tubular member 34 will be piloted within the supporting member 79 of the nozzle assembly 78, so that drilling fluid pumped down through the drill pipe B and mandrel passages 67, 68 will be discharged into the nozzle assembly passage 84, where it will be distributed through the lower nozzle 87 onto the bottom G of the hole, and through the lateral nozzles 88 directly onto the lower teeth of the expanded cutters 29.

Drilling weight can now be imposed upon the apparatus while the drill pipe and the apparatus are rotated at the proper speed, the lower cutters 78 rolling around the bottom of the hole to drill it away, and the upper ex panded cutters 29 rolling around the formation shoulder F to enlarge the well bore.

When it is desired to retrieve the apparatus A, the drill pipe B is elevated, to raise the apparatus until the casing shoe E is reached. The expanded cutter supporting members 21 will engage the casing shoe which will prevent upward movement of the body 15 of the tool for the time being. However, the tubular mandrel 12 can be pulled upwardly with respect to the body 15 against the force of the tension spring 50, elevating the expander member 33 above the expander surfaces 32 and the lower end 69 of the tubular member 34 above the cutters 29, until the kelly shoulder 18 engages the retainer ring 19 at the upper end of the body. Upward movement of the drill pipe B and mandrel 12 will then be transferred to the body 15, which will force the outer surfaces of the cutter supporting members 21 against the shoe F and cause the latter to shift them, and the cutters 29 carried thereby, inwardly to their fully retracted positions, the inner ends of the cutters 29 again being disposed closely adjacent each other at the axis of the body 15, inasmuch as the lower end 69 of the tubular member 34 is then disposed above the cutters 29. The drill pipe B and apparatus A can then be elevated in the well casing C, the cutter supporting members 21 merely sliding along the wall of the well casing, until the apparatus has been removed from the casing at the top of the hole.

The inventor claims:

1. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward move ment of said cutter means from such outward position, said expanding means including a tubular member in said body and having its lower end disposed above the upper end of said fluid passage and above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cut ter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage.

2. In a rotary well drilling bit: a main body having a lower fluid passage; circumferentially spaced cutter supporting members mounted on said body for lateral move ment with respect to said body; cutters on said supporting members; means engageable with said cutter supporting members for expanding said cutter supporting members and cutters laterally outward and for preventing inward movement of said cutter supporting members and cutters from said outward position, said expanding means including a tubular member in said body having its lower end disposed above the upper end of said fluid assage and above said cutters when said cutters are in retracted position within said body and lying closely adjacent the axis of said body; said tubular member moving downwardly of said body between said cutters and into said lower fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid into said lower fluid passage.

3. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from such outward position, said expanding means including a tubular mandrel connectible to a drill string and slidably splined to said body, the lower end of said mandrel being disposed above the upper end of said fluid passage and above said cutter means to allow said cutter means to lie closely adjacent the axis of said body when in retracted position; said mandrel moving downwardly of said body along said cutter means and into said fluid passage, as said cutter means is expanded outwardly, to conduct fluid from the drill string into said fluid passage.

4. In a rotary well drilling bit: a main body having a lower fluid passage; circumferentially spaced cutter supporting members mounted on said body for lateral movement with respect to said body; cutters on said supporting members; means engageable with said cutter supporting members for expanding said cutter supporting members and cutters laterally outward and for preventing inward movement of said cutter supporting members and cutters from said outward position, said expanding means including a tubular mandrel connectible to a drill string and slidably splined to said body, the lower end of said mandrel being disposed above the upper end of said fluid passage and above said cutters to allow said cutters to lie closely adjacent the axis of said body when in retracted position; said mandrel moving downwardly of said body along said cutters and into said fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid from the drill string into said fluid passage.

5. In a rotary Well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; a tubular mandrel connectible to a drill string and slidably splined to said body; coengageable expander means on said mandrel and cutter means for expanding said cutter means laterally outward of said body as said mandrel moves downwardly relative to said body; the lower end of said mandrel being disposed above the upper end of said fluid passage and above said cutter means when said cutter means is in retracted position within said body; said mandrel moving relatively downward in said body along said cutter means and into said fluid passage, as said cutter means is expanded outwardly, to conduct fluid from the drill string into said fluid passage.

6. In a rotary well drilling bit: a main body having a lower fluid passage; circumferentially spaced cutter supporting members mounted on said body for lateral movement with respect to said body; cutters on said supporting members; a tubular mandrel connectible to a drill string and slidably splined to said body; coengageable expander means on said mandrel and cutter supporting members for expanding said cutter supporting members and cutters laterally outward of said body as said mandrel moves downwardly relative to said body; the lower end of said mandrel being disposed above the upper end of said fluid passage and above said cutters when said cutters are in retracted position within said body; said mandrel moving relatively downward in said body between said cutters and into said fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid from the drill string into said fluid passage.

7. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from such outward position, said expanding means including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cutter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage; and nozzle means communicating with said fluid passage and adapted to discharge fluid from said passage directly onto the lower portion of said cutter means when said cutter means is in expanded position.

8. In a rotary well drilling bit: a main body having a lower fluid passage; circumferentially spaced cutter supporting members mounted on said body for lateral movement with respect to said body; cutters on said supporting members; means engageable with said cutter supporting members for expanding said cutter supporting members and cutters laterally outward and for preventing inward movement of said cutter supporting members and cutters from said outward position, said expanding means including a tubular member in said body having its lower end disposed above said cutters when said cutters are in retracted position within said body and lying closely adjacent the axis of said body; said tubular member moving downwardly of said body between said cutters and into said lower fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid into said lower fluid passage; and nozzles carried by said body and communicating with said fluid passage to discharge fluid directly onto the lower portions of said cutters when said cutters are in expanded position.

9. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movementof said cutter means from such outward position, said expandingmeans including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cutter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage; a pilot bit secured to the lower portion of said body and having lower cutters adapted to operate upon the bottom of the hole being drilled; and nozzle means for discharging fluid from said passage toward the bottom of the hole being drilled.

10. .In a rotary well drilling bit: a main body having a lower fluid pas-sage; circumferentially spaced cutter supporting members mounted on said body for lateral movement with respect to said body; cutters on said supporting members; means engageable with said cutter supporting members for expanding said cutter supporting members and cutters laterally outward and for preventing inward movement of said cutter supporting members and cutters from said outward position, said expanding means including a tubular member in said body having its lower end disposed above said cutters when said cutters are in retracted position within said body and lying closely adjacent the axis of said body; said tubular member moving downwardly of said body between said cutters and into said lower fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid into said lower fluid passage; a pilot bit secured to the lower portion of said body and having lower cutters adapted to operate upon the bottom of the hole being drilled; and nozzle means for discharging fluid from said passage toward the bottom of the hole being drilled.

11. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from such outward position, said expanding means including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cutter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage; nozzle means communicating with said fluid passage and adapted to discharge fluid from said passage directly onto the lower portion of said cutter means when said cutter means is in expanded position; a pilot bit secured to the lower portion of said body and having lower cutters adapted to operate upon the bottom of the hole being drilled; and nozzle means for discharging fluid from said passage toward the bottom of the hole being drilled.

12. In a rotary well drilling bit: a main body having a lower fluid passage; circumferentially spaced cutter supporting members mounted on said body for lateral movement with respect to said body; cutters on said supporting members; means engageable with said cutter supporting members for expanding said cutter supporting members and cutters lateraly outward and for preventing inward movement of said cutter supporting members and cutters from said outward position, said expanding means including a tubular member in said body having its lower end disposed above said cutters when said cutters are in retracted position within said body and lying closely ad- 1 1 jacent the axis of said body; said tubular member movin downwardly of said body between said cutters and into said lower fluid passage, as said cutter supporting members and cutters are expanded outwardly, to conduct fluid into said lower fluid passage; nozzles carried by said body and communicating with said fluid passage to discharge fluid directly onto the lower portions of said cutters when said cutters are in expanded position; a pilot bit secured to the lower portion of said body and having lower cutters adapted to operate upon the bottom of the hole being drilled; and nozzle means for discharging fluid from said passage toward the bottom of the hole being drilled.

13. In a rotary well drilling bit: a main body; cutter means mounted on said body for lateral movement with respect to said body; said body having a fluid passage extending below said cutter means; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from such outward position, said expanding means including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retacted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cutter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said iluid passage.

14. In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from said outward position, said expanding means including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said cutter means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage; and means communicating with said passage for discharging fluid therefrom when said tubular member is in said passage.

15 In a rotary well drilling bit: a main body having a lower fluid passage; cutter means mounted on said body for lateral movement with respect to said body; means engageable with said cutter means for expanding said cutter means laterally outward and for preventing inward movement of said cutter means from said outward position, said expanding means including a tubular member in said body and having its lower end disposed above said cutter means when said cutter means is in retracted position within said body closely adjacent the axis of said body; said tubular member moving downwardly of said body along said tubular means and into said lower fluid passage, as said cutter means is expanded outwardly, to conduct fluid into said lower fluid passage; a pilot bit secured to the lower portion of said body and having lower cutters adapted to operate upon the formation being drilled; said passage having an outlet for discharging fluid therefrom when said tubular member is in said passage.

References Cited in the file of this patent UNITED STATES PATENTS 2,238,998 Grant Apr. 22, 1941 2,545,036 Kammerer Mar. 13, 1951 2,545,037 Kammerer Mar. 13, 1951 

1. IN A ROTARY WELL DRILLING BIT: A MAIN BODY HAVING A LOWER FLUID PASSAGE; CUTTER MEANS MOUNTED ON SAID BODY FOR LATERAL MOVEMENT WITH RESPECT TO SAID BODY; MEANS ENGAGEABLE WITH SAID CUTTER MEANS FOR EXPANDING SAID CUTTER MEANS LATERALLY OUTWARD AND FOR PREVENTING INWARD MOVEMENT OF SAID CUTTER MEANS FROM SUCH OUTWARD POSITION, SAID EXPANDING MEANS INCLUDING A TUBULAR MEMBER IN SAID BODY AND HAVING ITS LOWER END DISPOSED ABOVE THE UPPER END OF SAID FLUID PASSAGE AND ABOVE SAID CUTTER MEANS WHEN SAID CUTTER MEANS IS IN RETRACTED POSITION WITHIN SAID BODY CLOSELY ADJACENT THE AXIS OF SAID BODY; SAID TUBULAR MEMBER MOVING DOWNWARDLY OF SAID BODY ALONG SAID CUT TER MEANS AND INTO SAID LOWER FLUID PASSAGE, AS SAID CUTTER MEANS IS EXPANDED OUTWARDLY, TO CONDUCT FLUID INTO SAID LOWER FLUID PASSAGE. 